I thought a high pitched whine would mean that the starter is not throwing the gear out far enough, could just be dirty, or knackered. where abouts in Cumbria are you from..........
Get a nights kip. Leave earlyish to drive down to Dover (or whatever port you're going from). Get a battery fitted near the port. Get on ferry. Get to France. Have a beer!!!
Yeh. You need to test it under load. I know it's a pain, but see what the volts do when the key is turned. Bet they drop right down.
border dubbers country........................ can you not just bump it to get you moving. are you getting a ferry as im sure they would make sure you got started again and then find a garage to fix you up. would stop the missus tears.............