Moggie, please excuse me if you know all this already but, if you are looking for short term gain, you need to take great care to understand the tax rules. You need to get out there just before the start of a tax year because you are only entitled to tax free salary if you spend a complete tax year out of UK (minus 90 days for holidays). So if BWoS try to delay your departure ('we couldn't get a visa' is the standard excuse) until just after the start of the next tax year, you would then not make tax free status until Apr 2006.
Should you get fired or so cheesed off you need to leave before completing a tax year, you will have a lot of paying Gordon Brown to do.
Doubtless you will have looked at some of this - good advice already given to contact someone out there - you'll not get the whole picture from Warton.