At 25 years old, I would personally forget about repairing your existing boiler. It is well past its best. I would also not bother with using the log/coal fire back boiler.
Whats your HW needs like? This is what matters when deciding on a combi or not, as well as your cold mains flow rate and pressure.
A better value for money boiler would be one of the Broag Avanta Plus range.
Easily works on LPG as the other 2 you have mentioned, better warranty, just as reliable, but a good couple of hundred pounds cheaper.
If the £2600 includes VAT and everything, I don't think it is too far out for changing to a combi.
Whats your HW needs like? This is what matters when deciding on a combi or not, as well as your cold mains flow rate and pressure.
A better value for money boiler would be one of the Broag Avanta Plus range.
Easily works on LPG as the other 2 you have mentioned, better warranty, just as reliable, but a good couple of hundred pounds cheaper.
If the £2600 includes VAT and everything, I don't think it is too far out for changing to a combi.