Shipment by air has more restrictions than shipment by ground. This would be a problem when ordering from the US. You might instead try locations in Europe for chemicals, I know that there are people in Germany who make there own processing solutions.
Hydroxylamine is a known carcinogen and probably the hardest of the ingredients to obtain. CD-4 is a skin irritant and I wouldn't eat it but not all that dangerous. Check with a university to obtain a small amount of formaldehyde since it is used to preserve specimens. The ferric-EDTA used in the bleach should be available as it is sold as a source of iron for house and garden plants. However, I find it too be rather slow in its bleaching action and prefer to use the E-6 ferricyanide bleach instead. Everything else is pretty much the same as for B&W processing.
Keep trying and don't give up just yet. Contact some camera clubs and see if they have sources for photochemicals in Britain. Thankfully the US and Canada have not yet reached the same level of paranoia that the UK apparantly has.