Hi everyone, newbie here!!
Would like some help with a new CH system.
We are currently building a single story extension to our bungalow which will turn it in to a 3 bedroom 1 bathroom, 1 en suite home. The current system is very old and not very efficient. Due to the new layout etc it has been suggested we install a new system to include a megaflow tank and a  boiler in the roof with all the new pipework in the roof and some underfloor heating in the extension (approx 12' x10'). We have a good reliable plumber in the family and he will be doing the work but just wanted some advice on the best manufacturers etc. Is this the best system? Any advice etc gratefully received.

We have UFH. Personally I feel it's better suited to houses where at least one person is home in the daytime. If you are both working I would go for rads. The reason is the longer warm up time from UFH. Rads are typically set to come on twice a day, perhaps backed up by a frost stat if it gets really cold when the heating is off. UFH by contrast can take a long time to heat a room so you end up setting it to come on an hour or two earlier than you would with rads. Just when it's warmed up the floor slab you leave for work leaving the UFH to cool down again. If there is someone at home all day then it's a different matter. In that case instead of programming the UFH to be off in the daytime you can just set it back a few degrees, typically 3-4.