Not necessarily. If you're already in the process of buying, there's probably already a Notaire involved in the sale/purchase - one Notaire acts for both parties here. And how did you manage to negotiate the purchase in the first place?
Since there's very little room for negotiation within a sales document, if you want the place, it's probably not worth going to the extra effort and expense of finding an English-speaking Notaire - unless, as Dej says, it's a complex transaction. AND, worth bearing in mind, is that unless they're a properly registered dual-language professional, what they tell you in English will have no legal standing.
It may well be a baptism by fire, but you really WILL have to learn to cope with the fact that everyone in France speaks French and all legal and official documents are in French, and they expect you to handle that (complete opposite to the UK!!!! I humbly suggest).
So .... time to get the dictionaries and grammar books out ....
However, all of that said, you're in an area of France which has a huge expat Anglophone population and if you ask around you might well find someone who's prepared to interpret for you on an unofficial basis if you really need them.
hils