You've got plenty of time to apply.
You can apply for a single entry tourist visa when you're 3 months or less before you're planned trip here, (so in your case you could have applied any time after Oct 1st)
The visa itself is valid for entry for 90 days from the date it's issued, so apply now and you'll have no problem. As long as you enter before the visa expires you'll get stamped in for 60 days (even if you entered on the very last day the visa is valid for you'd still get stamped in for 60 days)
Sadly the questions you're asking are totally irrelevant as far as how fast you will or won't get your visa. It comes down to how completely you fill out and upload the required documents, don't upload what they want where they want it, they'll send you a request for additional documentation and it'll stretch out the processing time..
I'd say apply now and you'll be fine,
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This is the processing time posted on the thai consulate in London website