Propane is essential if you desire to have the bottle outside piped to the inside throughout the year as butane ceases to work if the temperature drops too low.
As far as gas bottles in the tunnel is concerned I did multiple 2 way journeys with a connected bottle without any problems.
I remember doing the same. Provided the cylinder is below 47kg and less than 80% full is what I read on the tunnel instructions when I checked as plenty of caravans travel with their gas cylinders attached as does my friend in his camper van.
Thanks - I’ll check the tunnel specifics.
I’m sure it’s possible to hide a gas bottle, but would prefer to follow the rules. 
Came back on Eurotunnel 20 March - no questions, no search. It was 5.30am though.
Bad idea.
As I said, I’d rather follow the rules.
I use similar to this all the bricolages sell them https://www.amazon.fr/dp/B08KDFV835/ref=cm_sw_em_r_mt_dp_J7R5GH4YVJ5H4Y1198ZC
Its keeps awning comfortable on an evening and the bell tent warm later on till my wood stove kicks in.
https://www.amazon.fr/GOZAR-Femelle-Connecteur-Libération-Caravan/dp/B07BHMFGJF/ref=sr_1_1?keywords=quick+release+butane+connectors&qid=1650355153&sr=8-1
These are the quick release couplers I use so that I can swap from heater to cooker quickly and safely.
Lastly a cooker similar to mine https://www.amazon.fr/Kemper-Camping-Cooker-Burner-30mbar/dp/B00BMPUUV6/ref=sr_1_3?__mk_fr_FR=ÅMÅŽÕÑ&crid=3CKBQ1BL8M9OJ&keywords=butane+cooker&qid=1650355537&sprefix=butane+cooker%2Caps%2C62&sr=8-3
Intermarché do their bottles much cheaper, I pay around 20€
Are they the same size? I noticed a slightly smaller set of gas bottles when I was over and thought the size was handy and a bit lighter.
Price comparison
Excellent article,
Answers all the questions.
Caravans travel across the Channel with their gas bottles, they just check that they are turned off. Worth a phonecall to verify.
In the UK propane cylinders are red and butane blue. Not so in France - here they are almost any colour. That fooled me when I first came here. The connections on the valves are not the same. Also you cannot legally or safely use a propane cylinder inside your property, it must be stored and connected from outside. My advice is to leave your camping stove in the UK and buy one over here, complete with a butane cylinder.
Thanks. Stella has already filled me in about the legality. We’ll be taking our stove because it’s not being used elsewhere and we don’t need to spend 70euros on another one.
As Corona pointed out above, we could take our existing gas bottle (6kg) on the tunnel because it falls below their limits, but it’s propane. Easiest, most cost effective solution will be to pick up a 10kg butane bottle from the local intermarche, plus a French regulator.
Loose LPG gas bottles are not permitted in the tunnel nor LPG powered vehicles. Only caravans and motorhomes with installed bottles are permitted.
Check if your camping stove uses bottle pressure or via a regulator. UK and French kg butane bottles have the same screw thread connection and are interchangeable but French regulator tends to be hand tightened whereas the UK version is spanner tightened.
No longer true. There are green, sand, red and blue bottles available depending on brand. Flogas has taken over many smaller suppliers in recent years.
This has propane prices on it scroll down to find them
Well I travelled through it many times with my Teardrop. The bottle was only secured by its weight and a couple of pieces of metal fixed to the floor stopping it from sliding about. Always passed inspection as long as it was switched off. Also news to me that it was illegal to have it ‘indoors’. Perhaps a good job that I no longer use it. 
Well, “a couple of pieces of metal fixed to the floor” could be construed as securely attached.
