Can anybody advise me the names and contact details for UK tool suppliers of heavy duty chain and chisel morticers, large dia circular saws and hand held planers ?

Ken, try Nathan Mcewen of NMA Agencies
They are the UK distributors for Mafell
E-mail Address(es):
nathanmcewen@ntlworld.com
Tel 01484 400 488
Ryobi Chain morticers
(Distributors include Carpenter Oak and Woodland) Ryobi are on
sales@ryobipower.co.uk
01452 724 777 for product info.
Carpenter Oak and Woodland resell at a marked discount to established users as a service to framers, (sort of like a co-op) therefore they do not deal with tech support, aftersales service, parts etc This should be carefully considered during the decision making process.
lastly for good 6" planers and 14" saws
try Makita, any local dealer, or Worcester Power tools who were at frame 2000
Beware of importing directly, there are some real issues surrounding compliance with current H&S regulations, liability etc.
new tools must have 'CE' Marking
the USA 'UL'marking is of no value in the UK and does not meet the more stringent CE standards.