For the leader tape and splicing tape, I can only make suggestions in total ignorance as to whether you’ll find them at these addresses:
http://www.easternelectronics.co.uk
http://www.mb-radio.co.uk
http://www.canford.co.uk
http://www.stirlingbroadcast.co.uk (still carrying a Merry Christmas banner!)
http://www.normanb.net (may be able to give a few clues – lives in Aberdeenshire and still has a lot of tapes in the cupboard).
http://www.ebay.com
tcarmanmedia-archives.org (Tracy is a dab-hand at what you’re trying to do and probably has a supply line set up for these items, albeit in the US. He can certainly provide invaluable tips & tricks to help you on your way – if you need it).(Good luck, and since Lady Penelope is vacationing at present I’ve told Parker you can have the car).
-Sean