Anyone in France can you advise on train ticket purchases please?

[Notquitegrownup]

Will post under Travel too, as this is really a holiday question, but we are off to St Malo area in three weeks, and fancy a day trip to Paris.

Are French train tickets available online as in the UK, and if so, can you recommend a link to a valid site?

Thanks

Sorry, should have googled first! Isn't the SNCF site easy to use?! Do hope that the UK sites are as easy for overseas travellers over here.

Paris here we come!