The problem is that you would be either puting a 13 amp unswitched socket or a 13 amp double pole switched fused connection unit onto 1 or 1.5mm t & e.
Though your use of it is probably not drawing anything more than some light fittings (though boilers are 3 amp fused they don't draw anything like that, less than an amp) someone else may come along and reuse it to full potential.
The radial circuit to accomodate a full socket or connection unit has to be in 2.5 t e minimum to carry 20 amps or 4mm t e to carry 32 amps (same as a ring main)
There is a school of thought that radials are safer than ring mains. There is also pressure to ban ring mains though most people don't feel it will happen.
There is no limit to the number of sockets or connection units you can have on a radial, just like a ring main and also like a ring main there is a maximum surface area. Without looking it up I think it's 75 msq instead of 100 for a ring.
There is nothing to stop you puting a boiler on a radial with lights if it were in 2.5mm t e but it would not be great practice.
Funnily the other day I was called to a boiler tripping the rcd. Their "electrician" rely had fitted a new db but not split rail. I quickly found myself back at the db looking for the fault and found the kitchen lights and the boiler on the same breaker. Disconnected lights and boiler no longer tripped rcd. Went to electrical supplier bought new 6 amp breaker put kitchen lights onto it. low voltage lamp bulbs often cause nuisance trips. I would have put in a split board and the lights and boiler (because it is a fixed appliance, so doesn't need protection and because I don't want it going off on a nuisance trip) would have gone on the non protected side. It's also good practice to put radials in the kitchen unprotected (because of the affect on rcd of combined leakage currents of the interference supressing circuits in kitchen appliances and damp kettles) but feed the appliances from fused cable outs with switch control above the worktop, so converting them to fixed appliances which don't require rcd protection. To do this with sockets wouldn't be good practice because some future user may not have a dishwasher and may use the vacant socket for portable equipment or for equipment outside.
You didn't expect a simple yes or no did you?
