I need to purchase a new used vehicle as my V-reg 1999/2000 Mk4 Astra 1.8 CD petrol estate has just turned over 170k miles and is nearing the end of its life. I am very keen to stay with Vauxhall and am looking at a low-mileage Mk5 Astra estate again but this time in diesel format, a 1.7-litre specifically, as I am doing +/-15k miles on average a year. I hope that you can help me with some decision-making?
Firstly, is this sufficient mileage to justify a diesel? I hear that doing +20k miles a year is perhaps the best starting point to justify a diesel purchase?

Secondly, l would like certain trimmings such as cruise control, trip computer and USB port for audio interface. Are all of these available in one specific model of Mk5 Vauxhall Astra estate?

Lastly, I am hoping not to spend more than +/- £4000 on said vehicle. If my requirements fall outside of my planned budget can you recommend an equivalent where these would be available?