Can anyone help please. I'm trying to find the Doctor Who episode where the TARDIS materialised inside itself!

I think it happened - It's a vague memory.

I think the Doctor was played by Peter Davidson or Colin Baker at the time.

Cheers.

it was a Tom Baker story Logopolis

Yep, Logopolis is probably what you're thinking of. It's not exactly the TARDIS inside itself though. It's the Master's TARDIS (which has temporarily disguised itself as a police box) inside the Doctor's one.

Thanks for the info.

I'll go and look it up on YouTube now!

You can get it on DVD. I fully recommend it. Loads of special features.