Advice for Newbie

Hi Guys, Firstly let me introduce myself, I'm Nick and live in the UK and I apologise in advance for what is likely going to be a lengthy post! I'm looking to dip my toe in the water and buy my first set of decent audio equipment. I've always wanted a decent setup but for one reason or another It has never happened. Anyway, I've recently started researching and reading around the forums etc for idea's on what I actually need and now is the time to ask the guys that actually know!

I've spent the last 3 months...(quite literally) ripping my 4000+ CD collection into FLAC format and now have all my music on a FreeNAS server at home. I've also got this backed up elsewhere. This will be my sole source for all my music. I had initially thought a SONOS system was going to be my best option as the ease of use and flexibility for the entire house is very appealing. Whilst I may in the future still get a couple of Sonos speakers for the bedroom etc I want my main two listening areas to meet my exact needs.

I plan to put this together over the course of the next 6 months, I'm in no rush to get every thing now. I've set myself a budget of £4000 maximum if needed but I'm obviously looking to do this as cheap as possible whilst still having a great setup suited to my needs.

So, I actually listen to most of my music in the office at home and this is where I plan on starting from. I'd like some advice but my initial thoughts are that I'd need either a DAC, AMP and a pair of speakers or alternatively just a pair of active speakers. I'm thinking that a DAC at least would be handy in this room for if I decided to connect these speakers up to a Sonos setup at a later date. The room is 5m x 5m and the speakers would be sat on a desk or up on a shelf. I'm really not sure what is for the best, would I need a SUB? how much of my budget should be spent in this room etc?

The second area is the living room and here the NAS which is located upstairs in the office would be the source for all the music. I'm really not sure what to do for the best in this room, If i understand things correctly I have zero need for a pre-amp so would I be best served with a DAC-AMP and speaker setup again connected to a Sonos connect so that I can control the music from my NAS using a tablet etc. Or do I go with an AVR for connecting to the TV or am I best keeping this separate? This is where I start to lose sight on what I actually need for the best.

I guess my main aim is to be able to add speakers in other rooms over time and have control of all of these from one device. I don't even know if there's a better option suited to this than Sonos?

I'll stop here, otherwise I'll start confusing myself again! Any advice or thoughts would be much appreciated.

Oh and as for the music I listen to, it's wide ranging. I guess it's mainly Indie, Rock and dance music but I have music stretching all genres. Some Favorites being The National, Oasis, Bob Dylan, Stone Roses, Rolling Stones, The Jam, Bob Marley..to name but a few.

Thanks in advance.