Do you think a British flat which accommodates a gas oven will also have the wiring in point for an electric oven?

im a builder ..uk have seen many properties with both ..however the cable is normally connected to its own MCB   circuit breaker ...but you can now buy ovens that have a 13amp plug on them ..so its an easier fix ..most kitchen worktops have a socket nearby 

If it's an oven with an integral hob it will need it's own 40 to 50 amp dedicated circuit with a control unit adjacent. If it's a built in oven many of these will plug into a 13 amp socket. A separate electric hob also required a dedicated circuit. It's pot luck with what you will discover. Bear in mind that a microwave with an integral grill can cook most things. You can also consider worktop halogen ovens too.

I think it won't.

Probably not.  No contractor is going to spend the money to install both bas lines and heavy duty electrical lines and breaker switches need for an electric stove, knowing that only one of them would ever be used.

The only way it would have both if is someone paid a lot of extra money to have the second connector put in place.

Hard to say; if you have a fusebox with a 13 amp fuse, then there is what is needed - if you have the room for an oven.