You're going to need a fairly hefty PA to run all that through.
We spent £900 on 2 tops and a sub, all Mackie (SA1521 x 2, SWA1501 x 1) and we wouldn't be able to run all that through it. I used to run my bass through it, and while it sounded great, it did affect the vocals, they were notably quieter when I was playing certain notes.
A quick list of what you'll need with estimated used prices:
2 powered Tops - 15" - £500 - £700 for a pair
2 powered Subs - 15" or 18" - £600 - £700 for a pair
Speaker stands - £20 each for sub to top poles or £45 each for floor standers
2 powered Monitors - 15" - £400 a pair
Vocal Mics - SM58s - £50-60 each
Kick Mic - essential! D112 - £60-70
Mic Stands - Studiospares.co.uk boom mics - £13 each
A Mixer - £100+ depending on the desk
Cables, lots and spares - £10+ each
You'll also need cases to keep everything safe and working.
We've probably spent that much over the last 12-18 months and have all the equipment listed above. Basically, I bought it all as and when I could afford it, then the band paid me from the following gigs. We also borrowed bits and pieces here and there until we had a full rig.
Personally, I think it's massively important not to skrimp on the PA, we get complimented all the time on our "sound", and the PA is a massive part of it. It's so frustrating to see a band play a song really well, but it sounds pathetic because they bought a cheap PA.