DIYbanter - Central Heating control unit replacement

A little question, if someone could help I'd appreciate it.

My heating timer control at home packed-up last week, resulting in the
heating being on all the time. The control is an old classic Randall 102.

I need a replacement, and B+Que in Chiswick have a large selection to choose
from. It's a pity their expertise isn't of the same magnitude. (Well,
actually, it is of the same magnitude, as, although they have some 15 - 20
models to choose from, they only offered me 3 that they had in stock, and
their heating expert doesn't working there any more. Their manager couldn't
even point me in the right direction, apart from Wickes, so I didn't hold
out any hope for qualified advice).

I'd appreciate an opinion and pointer in the right direction for a
replacement.

My old gas back boiler (with gas heater, a BAXI Bermuda 551) has a
thermostatic control dial on the unit. This is the only temperature control
I have. I assume it's taking the heat of the return heating supply. The only
other control I have is the said ban-jaxed Randall 102.

Cables going into the Randall is 240v mains and, I assume, the other cable
is the control cable to the gas boiler / heater.

I could just get a simple replacement timer unit, but I think is should be
possible to get a control timer unit with a separate room thermostat hard
wired back to the control timer unit.

Does anyone have any suggestions as to either a heating control unit, or HCU
& room thermostat combination?

Seasons regards

Damian