Okay the pressure gauge was on zero so I've re- pressured it but it's gone to 2!
I cannot bleed the radiator as I don't have any tools
I haven't turned the power back on yet but will it be okay at two?
It's not in the red area
As its not been running for six months, you might have some air in the system. Put the heating on and run it for an hour or so. The circulating pump may be noisy for a while due to lack of use.
UPDATE - I managed to get it at 1.5 - all was going smoothly and I went to the flat downstairs. When I returned there was a heavy drip - not a stream but more than the odd drop - coming from one of the pipes.
The flat was at an ok temp so I turned the power off and placed towels and a bowl underneath. The boiler was installed by British Gas not sure how long ago - no more than 7 years probably a couple of years less, but I cancelled the home care package last year as no one was living here - still it might be under their 5 years warranty
Thank you for all your help I certainly feel confident to increase the pressure should it happen again
Sorry to come late to the party, Ric, but you've had some good answers already.
Combi boilers are fitted with an internal "pressure relief valve" which will blow off any dangerous excess pressure automatically. This varies, but often around 3 bar pressure.
When the radiator circuit is hot, it's perfectly normal for system pressure to rise by quite a bit. Maybe between 1.5 and 2 bar. Water expands on heating ... thus a normal pressure increase.