Hi mate,
I've been playing in and out of bands for about 25 years now so hopefully i can point you in the right direction.
I suppose the easiest way to answer your question is to decide upon the material you want to play as this can determine which rig you use. £250 is not a great deal of wedge to get a quality amp, yet again i suppose it will depend on how much you want to use it. 50 watts is quite powerful mind, i used to drag 100 watt heads with a 4x12 cab around, now you can easily gig a pub with a 15 watt valve amp - valve amps are considerably louder than transistor based amps, therefore you only need a lower wattage.
I've used all standards of marshalls (including plexi's, dsl and handwired) and generally these are more suited for rock/blues stuff, ebay is great for second hand gear and marshalls can last forever if they are looked after so dont be afraid of buying second hand ( i have a nice fender acoustic on ebay at the mo if your interested!)
Marshall DSL (Dual super lead) (all valve)are a fantastic range of combo's and heads and i would highly recommend any in the series, second hand you could prob get a 50 watt combo for a little over your price range, but worth it. They come with a footswitch to easily switchable between the channels.(clean/overdriven/filth!! - and reverb on/off)
For cleaner jangly/country/indie, Fender could be the way forward, deluxe reverbs are great and the hot rod series are highly acclaimed. Blackstar amps are simply awesome but are very expensive.
Amps with built in effects are ok, but generally considered to be used by people who rely more on effects than technique and tone.
With regards to effects, dont be fooled into the 101 effects all in one box scenario (multi-effects units) they are on the whole bad - and you will lose all the natural tone from your guitar., you are far better off taking your time and buying some decent Boss pedals and linking them with patch leads. In my experience these pedals will cover all bases:
BOSS TU3 -TUNER
BOSS DD3 - DIGITAL DELAY
BOSS CHORUS PEDAL
IBANEZ TUBESCREAMER
JIM DUNLOP CRY BABY - (YOU'VE GOT ONE!!)
velcro/foam them into an old suitcase size flightcase, and there you go you are all pro'd up!
Budget amps are generally transistor (as is your dfx) and cant compete with a valve amp for tone/feel and sound. If you can push your budget up a little and have a look at some of the amps i've reccomended.
Anyhoo i've ranted on, any probs let me know,
Cheers BT