I have used Garmin explore on Mac to insert 150waypoints, these are now available on the app and on my watch however when I attempt to create a route from my collection in waypoints it doesn’t let me select any... have I got to many waypoints?

I assume you're talking about accessing the web site explore.garmin.com from your Mac, as opposed to using the Explore app on an iOS mobile device. Either way, routes are drawn on the map, not constructed by connecting waypoints. Since you can see the waypoints on the map, you can visually construct a route by drawing a line between successive waypoints. But the waypoints are just a visual aid, not really part of the route.

Does that answer the question, or am I missing something?

I have been back and had a look And understand what you mean, how for example could I create a route for example with 10 of these from a list say number 23,45,78,12,14 so it would give me range and bearing to the first, then scroll to the second

That's exactly what route is. You would draw visually draw the route line starting at 23, then through 45, 78, 12, and 14. End the route at 14. Now, when you navigate the route, it will initially navigate to 23. When you pass 23, it will start navigating to the next point on the route - 45. And so forth. 

This works in the obvious way as long as you pass "near enough" to each waypoint to register "arrival". If you navigate off the route and "miss a waypoint", it should pick up at the nearest point "ahead" on the route. You probably won't have any issue with that in open water. But it can sometimes present issues with land navigation, particularly if the route doubles back on itself or something like that.