I want a 1 year visa based on marriage my Thai wife is having a baby.. I am from the UK is it better to do visa here or when I arrive on a 30 day visa exemption at the Airport? What papers do I need also...Thanks

Here must be the UK and you would need paperwork of marriage to obtain a single or multi entry (1 year) non immigrant O visa (for up to 90 day stays) from a Thai Consulate. You would have to check with Consulate exactly what they require but for sure marriage certificate/copy and normally copy of wife ID card or other proof of current relationship (letter from wife or such)

I suspect what you may actually want is a one year extension of stay from Immigration in Thailand based on marriage and having 400k in local account 2 months or 40k per month income?

You get a visa before leaving the UK.

You can get a multiple entry non-o visa that will give unlimited 90 day entries for a year.

You could also get a single entry not-o visa and then apply for a one year extension of stay based upon marriage. You would need 400k baht in a Thai bank for 2 moths or proof of 40k baht to apply for the extension.

You can apply for either visa in person or by post at the embassy in London.