Horne made a try-scoring comeback in last weekend’s 46-25 win over Benetton but knows competition for the No 9 jersey is fierce.
Ali Price and Jamie Dobie have rejoined the squad after international duty and both are likely to be in the mix for selection for the last-16 tie in the south of France.
Scotland sevens cap Sean Kennedy is also available as coach Danny Wilson ponders his team selection.
Horne suffered a foot injury while training with Scotland during the Autumn Nations Cup which took longer than expected to recover from.
“We were doing a general training practice and I got my foot in the wrong position and ended up needing surgery to clean up my toe,” explained the 25-year-old. “Not ideal. I was out for six weeks before my op and 12 weeks after my op. It was quite a long time to get back fit.”
The scrum-half admitted he was “blowing a bit” during the win over Benetton but is desperate to play more in the latter part of the season.
“Europe is always exciting and you get the chance to test yourselves against different teams. Montpellier are a massive club so it will be fun first of all and then the Rainbow Cup where we will play some of the South African teams we haven’t played before.
“There is a lot of competition for scrum-half and we will all be pushing each other and hopefully put our hands up to start.”
Whoever gets the nod is likely to be up against Cobus Reinach, Montpellier’s South African scrum-half who was part of the Springboks’ 2019 World Cup-winning squad.
“We have done a wee bit of research on them,” added Horne. “They have a big physical pack and will try and bully us up front. They have Cobus Reinach who is a great player and a lot of X factor players and big names so we’ll have to be at our best to beat them.
“I like to move big packs around so we have to keep the tempo high, go through multi-phase, tire them out and hopefully we will get a result off the back of it.”