Yup! This is the most difficult thing about an outdoors oriented channel. Something I want to cover on my new channel helping outdoors adventurers make content and build their channel even with limited opportunity to make said content. Here are a few things I've learned after a few years of building a fishing channel:
1. One Trip, Multiple Videos
When you do make a trip, plan and make as many videos as you can. Preferably plan entire playlists. In other words instead of documenting just the trip itself--which can be several videos long--plan a series of tutorials organized into playlists. This way one trip can yield up to 20 videos or more. Yesterday I filmed 8 videos for my new YouTube channel.
2. Make the Most of Your Time at "Basecamp"
You said that you were in England. I know a lady--
Jessica Mills from Homemade Wonderlust--who has a highly successful hiking channel. It is impossible for her to hike the Appalachian Trail everyday or every week. She may only be plan a long hike once a year or once every other year. Between that time she does lots of product reviews, and lots of live stream thing building her community.
3. We Are Limited to the Planet's Pace
Understand that our niche as outdoors adventurers is limited to the pace of the planet itself. I can't make new moon come around any faster. That when the fish bite. So our growth has to be taken at a slower pace; you have to plan for the long term, and that's okay.
4. Enjoy the Journey
Just enjoy the process, journey and struggle of building an outdoors YouTube channel. Many people don't have the opportunity to travel or fish, hunt, mountain climb, overland. The main thing is to inspire, entertain and help other either do the same or have them enjoy the outdoors through you in some way. If your audience detects that you are more concerned about subs and views instead of helping them experience the outdoors, they won't hang around long.
5. Mix-Unify Your Content
The old help-hub-hero model of content does apply, but for us as outdoors adventurers we often have to blend the content types together. My audience does like tutorials at all. So my help content is now less than 2 minutes. And my hub content in integrated into the hero content. Because my outdoors adventure are more like documentary film, I turn the camera around, and it's as if they are experiencing what's happening instead of me telling them about it.
6. Stoke the Conversation
Reply to every comment. Start and stoke the conversation. Use your video comments as a kind of forum. Ask question in the comments of your videos.
7. Keep Plugging Away
You have to keep going. It just takes us longer as outdoors adventurers, but you have to keep going.
8. Look at Other Outdoors YouTube Channels
Take a look at other Outdoors YouTubers and see how they have tackled this problem.
Andrew St. Pierre White--a real TV personality--builds 4 wheel drive trucks, then drives them across deserts of Australian and African. Well he obviously can't build a new truck every week, and he may only be able to plan an expedition once sometimes twice per year. He spends a lot of time telling stories in his home studio because he has such a rich background having travels around the world so much.
Let us know if this helps!