Ferroli Optima 901 Boiler?

Ferroli Combi Boiler Optima 901?

Niggling fault which seems to be getting worse.
If the boiler is not used, i.e you have not run hot water for a while and no heating is on when you come to run hot water you do not get any. If you go to the boiler the fan is running, this not normally running when the hot water is working. If you turn off the power, change the control to constant heating / hotwater and wait for 10 seconds then turn on the power, after the blue flame roars run some water it will be ok for a while again - and the fan will stop running / be silent. This gets worse in the summer, maybe temperature or maybe because the heating is not in use. Today the pilot flame has been going out in addition so you have to go throught the full re lighting hassle! The boiler will also have the fan running during the night whilst trying to sleep, for no apparent reason! Any ideas appreciated very much!
A new development is the pilot light keeps going out when the weather is hot? Is there some temp sensor that could do this?