Ok guys I have some updates, but before I continue:
So now I realise now what was initially missing from my installation!
I'll give you all a hint:
Led Zeppelin, The rolling stones, Queen and of course, The Beatles.
Still clueless??
Ok, this picture may help:
Answer: Rockers (formally known as rocker pipes)
So what I decided to do was use a double socket fixed 45* from soil pipe into a rocker pipe which from there enters the IC inlet. Now, exiting the outlet, I've added a rocker there, then a single socket 20* which goes straight into a slip coupling (to allow for any movement/ settlement) and then a short offcut which goes into a single socket 10* which goes straight into the ac4000 adaptor. All good up to now? I think it's a huge improvement; it feels more secure and robust and it simply just looks more professional. So again, from the main inlet we see the rocker pipe which enters the branch, so do I just bridge from there straight to that multiflex bend which connects directly to tick gully? I have absolutely no problem using the multiflex here where the gully is concerned and I feel that this is their only place in the installation.
So again, many thanks to Hugh for his great advice and to be honest, it was so much easier doing this having seen Ian's work; just observing the way he'd placed his fittings. The only thing that I haven't done (unless there is anything else?) is laid the IC on a bed of concrete which I am aware of, however, I only realised this when I returned home with the fittings and didn't have cement so what I've done is laid it on a level slab to give the IC support and the IC is perfectly level. If it's going to be a massive problem, I'll relay the IC when I commence work at the front of house later on in the year, but I personally don't see why a slab wouldn't suffice? Every video/ picture I've ever seen, I've only ever seen the IC (whether shallow or deep) laid on 100mm pea shingle and simply backfilled.
I'll just need a bit of advice for the next phase and then I should be ok, but what I propose to do now is extend the branch with 600mm pipe, then attach slip coupling, extend another 600mm with pipe, slip coupling again and then another 1800mm pipe makes a 3m run and attach branch to spur off to gully.
After that, extend the run again this time 2m (allowing spaces for slip couplings as before) and install another tick gully, use a raising piece with rainwater adaptor for 68mm down-pipe straight into top of raising piece. If I'm not on the right track, let me know please! I'll post up some new pictures soon anyway.
Thanks guys!
A top down view if it helps: