30 miles/day, even 7 days a week, doesn't sound enough to warrant a diesel - IMO, you need to be covering 15,000 miles/year to justify the extra cost of purchase and repairs compared to fuel cost savings.

Don't get hung up on Isofix points - most child seats on sale in UK are designed to be attached by the seat belt.

Do you really need an estate? Most of our parents coped quite well with a medium hatchback, which would give you a wider range of cars to look at, particularly Japanese cars like my mk1 Mazda3 1.6 petrol which (in hatch form) has a 360 ltr boot. Similarly with the Honda Civic and Toyota Auris (you'd be looking at a 7+ yo car for that price unless its done a large mileage). Japanese petrol cars are mostly bomb-proof (my 10yo Mazda3 hasn't [touch wood] let me down yet and keeps passing its MOT with flying colours).

I doubt if you would need to look at the estate version of the Octavia, as their hatch verson has a huge 500+ ltr boot. Given your prferance for reliability, you may wish to read HJ's reviews (Reviews/Car-by-car section, see lower down for the older cars - don't be put off by the 3 or 4/5 stars for some, as they are often comparing them to newer cars and, with mine at least, they include an apparently 'dodgy' diesel range (same issues as the Fords they shared them with).

Honda and Toyota diesels appear to be reliable though, but well out of your price range I suspect. Best to stay with a petrol unless doing over 20k miles a year (the current small disparity between petrol and diesel prices at the pumps won't last) at least, especially if the 30 miles per day (11k miles a year) is made up of lot of short journeys to the shops, gran and grandad and (eventually) to the local nursery/school and back.

I now do about the same weekly mileage as you (34 miles a day 5 days a week to work and back plus about 3500 miles other than that per year [approx. 12.5k miles p.a.]) and still would go with Japanese + petrol + C-sized (Focus/Mazda3/Golf sized with a 350 ltr boot) car. You may be able to pick up a decent estate (for the extra space) for some, though you probably limit the range of models/sub-models on offer (e.g. Mazda don't do an estate of the 3).

Be careful about choosing a VAG (VW/Skoda/Seat) with either a diesel or chain-cam petrol engine (DO NOT choose a VAG DSG automatic!) - you need to cehck the 'Good & Bad' sub-section of each review as many VAG cars have long-standing serious issues with some (but not all) of their engines. Similarly Mazda and Ford with their diesels, especially the smaller engined ones. As others have said, such diesels like regular long trips and regular (more than the manufacturers say) servicing/new oil. Petrol's (proven and reliable) the way to go for you I think, especially when on a low budget.

You've got lots of good advice above: I'd just add one thing. I go along with most of what Engineer Andy says, except that personally I would go for an estate. Skoda estates, for example, are very little longer overall than the related hatchback: the same may well go for the Kia Ceed, which you can look up in the review section on this site (go to specifications).

Babies and their assorted equipment take up more room in a car than you can ever believe.

Ultimately for £3k condition matters more than make or model: try to find something that has a service history (which can be proved) and looks well cared for (which can't, but there will be clues).

If it were me, what would I end up with? Possibly something Japanese or Korean, if I could find one - but probably ending up with a petrol Focus becasue there are more of them around to chose from.

A colleague at work who also has two children is taking delivery of his new family car in a fortnight. IMO the ideal car: a brand new 5.0 litre Mustang!

Even with 2 kids I always had a saloon. A Rover 800 when they were young and a Saab 9-3 now. Both have impressive boots. The Saab is available in wagon form too if you really need. For 3 grand you'd be able to find a really well cared for 2008-9-10 ish example. With young kids on board, you can't argue with Saab safety - tough old birds, I know I crashed mine and then rebuilt it. I'd go petrol though, your mileage doesn't warrant diesel and the mechanical risks they bring.

We've found for a family car, by far the most important factor is how usable the boot is. In particular, you need to be able to get a folded buggy across the back of the car flat on the floor so the parcel shelf can close correctly.

This takes out a surprising number of cars which have apparently large luggage space (at least when measured in litres). We dismissed an Ibiza estate for this reason, and I suspect the same would be the case for the Fabia as both are quite narrow cars.

Your best bet with 3k to spend is something reasonably common, but a bit unfashionable, and slightly too small to be popular with minicab drivers. The Ceed would fit in this list (though I think you've be ok with the hatch which may be cheaper), as would the Hyundai i30 or a Toyota Auris. A Focus or Astra would be ok too, but avoid a Golf, A3 or BMW 1 series as you'd be paying £2000 for the badge and £1000 for the car in that case.

The Octavias now worth about £3k are from the era of not very good petrol engines (the 1.4 is absolutely awful to drive, the 1.6 not much better, and the 2.0FSI which does drive ok prone to using nearly as much oil as petrol). Most of the Diesels will have been snapped up by minicab drivers, but if you can find a 1.9TDI in decent conditon for the right price it would be a good choice though.