Alternative to oil fired central heating

They are not easily retrofitted, you will likely want to rip up floors and lay pipes for underflow heating if you switch to heat pump, otherwise it may not give enough heat into the house using rads alone.

I put in 7 Mill rads last year after my ofc failed, bit of messing round with app on timings/ temps but good so far, I’ve a stove also

Heating systems don't heat your house …. they replace the heat that is lost from the house

So, despite all the improvements you've made, it sounds like you still have a major heat loss issue to find and sort out before thinking about replacing your heating source.

The fact that you have a dormer my money is on air leakage as the main culprit.

I'v heard many horror stories about retro fitted heat pumps and personally know of two rural bungalows both 1990 built who spent a small fortune up grading insulation, new windows etc. etc. all as specified by architects and overseen by engineers. In both cases the oil fired heating was binned and replaced with an ultra modern air to water heating system…………to cut a long story short after over three years of astronomical electric bills and freezing houses both are back to square one again using oil. The only positive is homes are much cosier and cheaper to heat with the ''gold plated'' upgrades carried out.