what is the best time of year to visit st petersburg. Is the winter really too severe to enjoy the place. I come from the south of UK, we have just had a fairly cold winter, but do not have any really cold weather clothing just heavy coat and boots etc. Is april or may better than october. We only want a 3 day break. Also how expensive is expensive i read a lot about eating out prices, are they on the same scale as london etc. we dont want top end restaurant just local restaurants etc.

The summer is the best time as St Petersburg is a city for walking. But if you can't go in the summer then anytime is OK. April can still be cold and have some snow left, May is warmer, October can start to be cold but snow doesn't usually come until November. Heavy coat and boots are fine with a hat (as long as the boots are not Uggs or anything like that). Usually you won't need heavy coat or boots from late April.
It can be as inexpensive or as expensive as you want. Local restaurants are not usually expensive. Sometimes the lunchtime buffets in hotels can be really good value and gives an opportunity to taste local dishes.

One expense you should check is the visa. Not sure what the cost is these days for UK citizens, but you'll need a letter of invitation to get the visa, which isn't usually free. It's a lot of hassle for just three days.

If you are into beatiful buildings and the arts it is hard to beat old St Petersurg of the Czars and you can see and do a lot in 3 days. I found it to be more expensive than most European and American cities I have been to but it was worth it. I hired a guide-something I never did before- so that I saw far more than I would have seen on my own.

The climate is cold - noting like you are used to. I would not go in winter since you will not want to do/see anything outside.

We were there in mid September and the first day was what I had expected - a little chilly. The following day and for the rest of the trip it was COLD and windy. I was wearing multiple layers (tee, turtleneck, shirt, sweater and jean jacket) and was COLD. And I'm used to a colder climate (NYC) and like cold weather. At a guess on those days the high temps were in the low 40's - below freezing at night - and the locals were wearing winter coats.

A friend of mine went for a Christmas holiday - with a mink - and froze outdoors. And they were told it was mild winter.

So I would definitely not do anything before the end of May or after September.

I've been several times in winter (it's a good place for New Year) and yes it's cold outside with snow but it does not prevent anyone from seeing anything. Temperatures about -5C to -10C are OK, lower or very windy conditions becomes unpleasant to walk around however temperatures won't be that low in April or October (average is between 10C & 5C but then who can tell as temps are 40C in Moscow at the moment which is unusual).

The visa fee is a big expense and UK applications go through an agency. It's not a hassle but it is expensive - 3/4 nights is a typical duration from the UK for a break in St Pete or Moscow. If a tour operator arranges the trip they will organise the visa (check Kuoni for instance).

Sankt Petersburg is one of the most beautiful cities on earth. Of course, summer is the best time to visit, but to explore a city, palaces, churches and museums any time of year will be okay. Either in October or April, just be prepared for cold and rainy weather.

When it comes to cost, Russia is a strange country. There are two types of businesses: those for Western tourists and those for Russians. If you go to a restaurant which is frequented by locals, you get a decent three-course lunch with a drink @ 3 GBP, but be prepared that they do not speak any language but Russian and that you have to decipher the Cyrillic menu (order the dish of the day). If you go to a fancy restaurant for tourists, you may end up @ 60 GBP per person. Same with hotels: there are several dozen 3-star hotels at less than 40 GBP as well as the Rocco Forte Astoria at 515 GBP (is IS a good hotel - I once stayed there before it was a Rocco Forte and when it was affordable).

An addendum:

I found that even taxi drivers have two kinds of fares. Tourists usually pay five times the fare that is paid by locals. However, the underground train is still very cheap.

Tickets at attractions are very expensive, too. Again, locals pay much lower prices.

We once hired a tour guide at the hotel. The cost was around 40 GBP for half a day. The guide offered to be hired privately for the next days - and then we paid about 10 GPB for a full day tour.