This one should be fairly easy: Radio.
Tum ti-tum ti-tum ti-tum
Tum ti-tum ti tahh, dahh
Tum ti-tum ti-tum ti-tum
Tum ti-tiddley tummmm
Tum ti-tiddley Tum ti-tiddley Tum ti-tiddley Tumm
Tum ti-tum ti-tum ti-tiddley
Tun ti-tiddley tum

Bom bo-bo-bo-bo bom-bo-bom-bo
Bom bo-bo-bo-bo bom bo-bom-bo
Bom bo-bom bo-bom bo-bom
Bom bo-bom bo-bom bo-bo-bo-bo....fade....

Do we have to guess one before moving on or providing our own?

[Kim] The Archers. [Btd] Right genre, wrong show.

I should say yes, otherwise its going to get very confusing. So far we have:
HB - Dit dit dit daa daa daa daa daa daa
Raak - Tump tumpa taaaa, ti-ti-tump-tee TUM tumpy tum tum TAAAAA, (Dr Who?)
on the go. Lets have some guesses or clues...

I should say yes, otherwise its going to get very confusing - addressed to Kims question...

[HB] Casualty?

[HB] Surely not the "Blessed" Z-Cars?

All wrong so far. You want a clue? OK - I quoted the ENTIRE theme.

Although "Breadmaster" had, perhaps, a subliminal idea ...

A clue to mine? Well, it's not Dr Who, and I didn't quote the whole thing, it sort of goes round in an endless loop, but here's some more starting from where the first part ended:

TI ti-ti TEEE, ti ti tee tee TEE TEE [rest] ti TEE TEE [rest] ti TEEE brrrrr
then repeat from start until the credits finish.