Noob, need help please

Here is a good write up explaining all of the inputs/outputs on an AV Receiver (All of these options won't be available on all receivers, but they will have speaker outputs).
https://www.themasterswitch.com/av-receiver-setup-explained   

Pre-Amp would not have the speaker connections, but could possibly have all of the others.

Read up and see what additional questions you may have.

As far as 2-Channel audio or Home Theater, keep in mind that to really enjoy a HT you are going to need to invest into a decent Video display as well. But it is best to determine the road you want to take and start down that path, buying and replacing equipment just ends up throwing more money at it down the road.

@laher, if you opt for a receiver that falls within the desired parameters being discussed, that's great.  The only thing I'd advise to get with it would be a second remote.  Doubtlessly it will likely have one....most of the 'major models' do...

Keep the battery out of it, and toss it into a nearby drawer.

The existing remote will likely get more use (and abuse) than anything else....and then there's the spilled drink, the dog, the 'misstep' in the dark, etc.

Likely this may occur later, when a direct replacement is 'N/A'.
These units are morphing almost as often as people change tires.

Other than that...do what fills Your desires and intentions, your ears, your esthetics...first. ;)  Paying too close of attention to 'Us' can make you crazy.*L*

Thanks for all the advice. 
In the U.K. I’ve never seen audio equipment at thrift stores. I’ll keep an eye out next time I go past some but ours are mainly clothes. 
So it seems that if I get an integrated amp I will get better quality but will not be able to add a center speaker which seems crucial for movies as it brings out the best in the dialogue. But if I go the AV receiver route then I can establish everything but won’t get the best out of my speakers for top quality when listening to music. This is the summary I am taking from all the comments, is that correct?

AV receiver definitely makes sense to get me going and to learn, and gives the most options. But as a couple people said, I don’t want to waste money by having to replace equipment. I’d rather get it right the first time.

Is it not possible to go the integrated amp route and add a center speaker down the line?

Can anyone tell me a couple high end AV receivers I can look into?
And equally a couple of integrated amps (preferably with built in DAC)?

Like i said before, if I need to stretch past 1k then I will. I just want to get the best out of the speakers and sub.

You got some suggestions for high quality AV receivers, add Marantz.  You really need to work with a British vendor.What your asking for otherwise is difficult.  You either want a "entry level" High End system with an integrated amp etc, or an AVR for movies..  I don't think combining them is easy as I'm sure you gathered from the various responses.

I believe one can purchase an integrated amplifier with home theater bypass. The integrated would drive the main speakers. Then one could purchase a modest audio video receiver to drive the center and surround speakers. The integrated would supply signal to the receiver via the HT output.