Hi Leedsample,
You no longer have to go to CAA HQ at Gatwick for an initial Class 1 medical, there are 3 other centres, see below:
http://http://www.caa.co.uk/default.aspx?catid=1859&pagetype=90&pageid=527
You might want to consider the NATS aeromedical centre at Prestwick as you're up north? Although, a day return flight from NCL to LGW is also reasonably handy I'm told.
Also, as you're ex-forces, are you eligible for and have you considered part funding from the ELCAS scheme? You have a decent pot of money already, but if there's some to be had, why not avail yourself of it?