Graham,
I'm in the same neck of the woods(no pun intended). I started by downloading the Stewmac tenor uke diagram as a pdf file. It's not a full plan, but it's a start and it's free. then I watched as many Youtube videos as I could. There is a series of instructional videos by Mya Moe Ukuleles which are very good and you will learn a lot from these. I think the company have packed in, but maybe the videos are still there, I don't know.
As for woods, you could start down the road at Tonetech, Stockport. Bill and Danny there are very helpful. Other places to try are Touchstone Tonewoods and David Dyke. Ebay is another source. Pete Howlett (member)also sells Uke sets occasionally so it might be worth a phonecall or a message over the forum.
best of luck Mike
I forgot to add that I had the 10-20 sander but moved over to a 16-32 when I started making guitars( and also there was a special offer on it at the time from Axminster Tools, Warrington)
The 16-32 is a much better and more powerful machine although the 10-20 is good enough if it meets your needs, but just be aware that you may, as I did, graduate to larger instruments in time.