I found this discussion extremely interesting as I have flown to both Helsinki and Tallinn from UK and would like to continue to St Petersburg next time.
I'd be very pleased to hear the outcome of the Eurocontrol discussion. I wonder if there are any rules that would require the pilot to be IR qualified for such international flights, as opposed to VFR according to IFR rules?
I've read that there's no Avgas at St Petersburg but the route Tallinn - St Pete - Malmi is just about possible in a PA-28 and there are closer places in Finland to land but I don't know how they'd react to an unscheduled G reg arrival from Russia!
Another issue is getting a visa for such an ad hoc trip. Apparently the Russian authorities require a visitor to have an 'invitation' from a travel agent for an organised tour before applying for a visa and probably require airline flight details as well. Evidently there are some 'visa experts' down by the Russian embassy in Helsinki who can arrange things for Finns but it turns out that a Brit can only apply via the Russian embassy in London, who require an invitation, etc.. Does anyone know the way through this?
BTW, Malmi EFHF airport in Helsinki is a wonderful place for GA and the approach proceedures as noted by Anton require staying clear of Vantaa but are not too difficult and the ATC is first class. You can land at Malmi even when it's closed.
Tallinn is also very welcoming if a little strange at first sight (you are escorted to a locked room without windows, monitored only by a video camera and a phone which mysteriously rings) but it is just their way of being helpful and it is a much cheaper place than Helsinki. They do seem to like long holds for arriving VFR traffic, but there was (in 2008) no problem with Avgas.