Wrong approach. You want to earn more and live closer, right approach.
If for arguments sake I valued my time at £10 an hour, thats a saving of £6525 per year, but because the original figure doesn't include fuel costs, I need to account for £1200 in fuel usage.
So £28,000 - £6500 + £1200 = £22,700.
So a salary of about £23,000 would seem about right, however to have the same take-home as before (disregarding the extra hours) it would need to be £29,200, which unfortunately is not really a realistic wage for this kind of position...
I wouldn't really see the point in moving job for the same wage youre on currently.
The move wouldn't be for the money, it would be to get out of a disorganised, stressful and failing MSP who have a habit of screwing around the staff and do not care about customer satisfaction, only profit and as a result are constantly shooting themselves in the foot and losing contracts - and to move into a more relaxed, close knit team, working on in-house systems and projects, with the potential of international business trips and the like, with a clear route of progression. Its a move for my sanity and happiness.
I think I'll say that I'm looking for around £25K, which is approaching the top end of the pay guide for this sort of role, and see what happens. If I feel the need, I could do overtime as well, and still be on less hours than before.