Plastic kitchen drain pipe needs to fix into ceramic soil pipe, nr Redruth Cornwall UK

My kitchen waste pipe discharges into a pipe going to my soakaway. It has now unsurprisingly become blocked (about 6 m from the drain). The soil pipe from the toilet to my septic tank passes underground about 1 m away from the end of the kitchen waste pipe with a good enough slope for the kitchen waste water to flow away easily. So ...

I'm hoping someone can give me an estimate for (a) unblocking the soakaway pipe (may need camera?) and (b) connecting the plastic kitchen waste pipe into the ceramic soil pipe.

Photograph shows rainwater drainpipe coming down at bottom right, next to kitchen drainpipe going across and incorrectly discharging into waterlogged drain. The drain pipe needs extending and a hole drilling into the ceramic pipe (just visible at top left of hole). Not sure whether the extended kitchen drainpipe extension should be metal rather than plastic since it may have to go above ground (visible is some concrete capping).

Anyone want to take this on? I've tried different ways of unblocking so it's been like it for a couple of weeks now. So no great
urgency (although I'm sometimes out there bailing the water when it rains).


Thanks

Arthur

Eta: I may also ask you to replace tap washer for brass kitchen tap.

Contact op via the pm system if you are interested