Pete
my ideal set up would be if money wasnt an object with your scope
eagleeye 10X lens
(this is needed to replace the swarwoski lens 20 - 60 lens or 32X its too powerful,although you can use the zoom on 20X setting it will give you an image the image will be large, in many circumstances too large, only head and shouldersof the bird !! )
eagleeye adapter 37mm thread diameter with matching collar
(to attach the camcorder to the lens )
Sony PC 120 Digital camcorder ( 37 mm diameter lens also has a stills facility to take pics) any sony camcorder with a 37mm lens check the specification on the sony web site
total cost now should be under a grand if you shop round PC120 might be scarce but should be available do a google search on "Sony PC 120"
You then may need to look at your tripod, is it sturdy enough ? do you need a video head attached to the tripod to take the weight of the scope and camcorder Manfrotto 501 video head 120 quid ? extra batteries, memory cards for taking pics if you are going to take pics ?
hope this helps ?
rgds
Paul