any recomendations for a smartphone?

I'd get one with as big a screen as you can afford. I bought a Samsung Galaxy SII for £380, without a contract and am well pleased with it. The iPhone is over £500 without a contract.

I got mine at prepaymania. They are currently sold out. (It was actually just under 375)
http://www.prepaymania.co.uk/mobilephone/simfree-samsung-galaxy-s2-i9100-sim-free-unlocked-mobile-phone.html

The Betfair app works fine, but mine displays one price as default and not matched amounts. (may be settings)
There's other apps for betfair, the zoombet seems very good to me. I presume it uses flash, as the update frequency is extraordinarily quick. (not tried settings)

You can use the full site and you can watch the videos for horse races you have bet on. You can watch RPTV for the Greyhound racing live as well.

I am on pay as you go. I have an O2 sim and a talk mobile one. O2 give you 500Mb of data (+ 300 texts) for 30 days when you top up a tenner, if you get on the right thingy.

Talk mobile charge 25p per day for the 1st 25mb of data. check their site for what they charge after. (not easy to find!) Talk mobile did an offer last month of 200 mins 200 texts and 2Gb data for ca 14 quid 2 year contract. (Double the normal data)

Talk mobile are offering "Unlimited" data plans at the moment, which seems very fair indeed
http://www.talkmobile.co.uk/paymonthly24smart.html

They say


Unlimited Internet (included in tariff allowance)

Some Pay Monthly contracts include "Unlimited" data access as part of the tariff allowance.
There is no limit on mobile internet usage on contracts which include "Unlimited" data access. However if we feel that your data usage is so excessive that other customers are detrimentally affected and/or we are concerned about fraud, we may introduce a fair use policy. If we publish a policy we will let you know. Any such policy may change from time to time, including where we introduce new Services which may require certain rules to ensure such new Services can be enjoyed by our customers. If, once we have implemented such a policy, your use of the Service is excessive, is causing problems for other users and you continue to use the Service excessively we may suspend all or some of the Services.

Thanks stow.