Question Author
Hiya GM.
Reporting back as requested... We've had the work done now, took a day longer than expected mainly down to bad wiring and the powerflush taking most of one day.
We now have lovely hot water in a fraction of the time, it stay hot for over a day and the boiler isn't constantly going on and off just heating the water.
The rads seem to heated up in the test, though we've not had them on again since.
All in all, pretty happy with the work carried out. Went with the guy in the first post.
Just one other Q if you come back to this... There's still loads of air in the system, which we can hear gurgling away and a rushing noise from the pump, when the hot water is on. How would we go about getting the air out? Obviously if we had the rads on, we could use the key to bleed them, but how do you go bleeding the hot water system?