Connecting flight to Koh samui

It's a breeze , your bags go through to Samui, in Bangkok you stay in transit and change planes. You do go through immigration in Bangkok but it's airside, very quick and is specific for travellers like yourself connecting to a domestic flight and takes no time at all. It's all clearly sign posted for you.

If you booked your 2 flights seperately make sure you can show your confirmed ticket from Bangkok to Samui when you first check-in.

If you booked with two different airlines then yes, you will have to clear customs at BKK, claim your baggage and then go through the boarding procedures for the second flight.
Did you book the flights yourself or did you use an agent? The only info on your profile is that you reside in the UK...so you don't need a visa for a short stay for Thailand.
Here is a link to the official BKK website.
http://www.suvarnabhumiairport.com/en/landings/passenger
And you'll see info on what to do with/without a boarding pass.

Since BKK has a huge, really huge terminal I'd suggest looking at where you'd arrive, where you'll clear customs and then where you'll go through boarding for the second flight. Here's a link to the map:
http://www.suvarnabhumiairport.com/en/124-within-the-terminal

And so we come to Bangkok Airways who have this helpful page:
http://www.bangkokair.com/pages/view/web-check-in
This is important as it has to do with how much time you'll need to plan on between arrival and departure:
"Web Check-in is available from 24 hours up to 2 hours prior to departure time.

Important note: Passengers on international flights who have completed web check-in are required to present themselves at Check-in Counter at least 90 minutes prior to departure time to obtain a boarding pass and verification of travel documents needed for Immigration and Security clearance."
Yep, 90 minutes. So your proposed flight to Samui isn't going to work...
and you haven't taken into account any possible delays on the Emirates flight. They're a great airline but no one can guarantee there won't be delays due to weather, etc.
AND...further down the page, there's a nice flow chart and it says the baggage has to be checked 2 HOURS before departure.
and since you'll be doing the reverse on your trip home, plan ahead now and check out what you'll need to do then...

One more thing (from another site):
"Transfer Lounges - Free lounges for the purpose of resting in between flights. Equipped with reclining leather chairs. Location: Airside, Concourse B and D (west side)"

Those who have used this airport will no doubt have their personal suggestions and experiences but this will get you started with all the official info.
Travel well and return happy....good luck

Sorry #2 but you are totally incorrect. Emirates interlines with Bangkok airways.

friendly,
Thanks for that correction. The OP spoke of the trip as two separate flights...if it's booked through then I was wrong. But if it's been booked as two separate bookings, then the OP should change it.

#4 no. It doesn't matter if the flights are in two seperate bookings as far as baggage is concerned, The bags can always be checked through to the final destination. OP may not get all his boarding passes in Scotland but is irrelevant as he goes to the transfer desk in Bangkok on his way to his new gate to Samui.

Where are you getting your information from ? It's very bad that pax can be so unnecessarily inconvenienced in this way if they believe this.

Frameo, ignore #2 and #4 completely. It's totally wrong.

Check your bags through to Samui ex- Scotland, showing details and docs for both carriers. You'll stay airside in Bangkok, clear passport control and the Bangkok Airways Transfer desk will issue you your next boarding pass. You'll clear Customs at Samui once you've got your checked baggage.

Emirates EK interlines with Bangkok Air PG as stated, and it makes no difference whatever whether you have one booking or separate bookings. Don't stress - you have plenty of time..........

Why do people ask this question AFTER booking and not before and why not first ask the airline?

I think that the problem with the earlier answer was a lack of familiarity with the airport and airline procedures regarding connecting flights

It's the nature of people to jump in with both feet, to make the commitment to fly, and then worry about the details later. Yes, you'd think it obvious that the first people to ask would be the airline, but they seldom do the obvious........and then they leave themselves wide open to all sorts of silly responses...............

Indeed.