Flyingtonka ......
Have been in the exact same situation with about the same experience. I would suggest you contact the CAA and apply for an assessment - I did this and was exempt from the navs but had to do all the techs which is at least a bit of a break. The only thing is that it was back in 1995 ( pre - JAA ) so it is probably different now but worth a try !
On the flying side , I saw Mike Smith at Heliair who thought that with my experience I shouldn't have to do anything !!! He found a reg. that said as long as I had more than 50hrs on my FAA ATPL they would give me a CAA one. I ended up doing a general handling flight in a B206 and got my ATPL.
Bit I think it has all changed with twin time and IR these days - but still maybe worth a go. Best of luck.
Tony.