What are the steps and timelines for obtaining a Tourist Visa for my girlfriend and a Non-Immigration O Visa based on marriage in Thailand?

A long post, sorry but everything I do now depends on which Visa I decide to get etc....I am 50yrs old UK male.

I am currently on a METV expiring on 6th May 2019. 1st May I hope to return to UK with my Thai girlfriend to visit my parents (her first trip). Then both of us return here to Thailand end May 2019 to continue our life together here.

We only have now about 7 weeks in Bangkok in total (as going to Buriram for a wedding end March for 1 week) and we require the following in that time.

1. My girlfriends Tourist Visa to allow her to accompany me to UK, which all can be done in Bangkok (no.1 priority)

2. Our Official Marriage, allowing me to obtain a Non-Immigration O Visa based on being married to a Thai national to return to Thailand, which I can obtain from the UK Hull Thai Consulate in May which is 10 km from my UK home. (no.2 priority)

3. Decide what Visa I am to return on, ideally The Non Immigration O Visa based on being married to a Thai national, but if we don't get married here due to time limits until we return end of May this isn't possible.

What is worrying me a lot (hence this cry for help) is I only have 7 weeks to do the marriage and the travel Visa for my girlfriend and I don't think I have enough time before May.

Would it be feasible to just apply for her Travel Visa now, then in UK me get a METV again, but I worry they may think I have had too many already (in 2018 I travelled to Thailand to see my girlfriend 4 times using 1 x Visa Exempt and 3 x SETV plus now my present METV) then end May when we return to Thailand do the official wedding paperwork when we have more time.

Sorry for the long question, but I have had many great responses to smaller single questions on here, but thought it better to show the whole story, thank you.....