A lot will tell you that outcalls are very few and far between.
I changed to outcall only a few years ago and my experience is this;
Yes most men want incall, and when offering incall there'll be hardly any outcalls. When I changed to outcall only there was a very quiet period, however over time I rebuilt a base based upon outcall clients - and there are quite a few. In the meantime I had to keep maintaining that I was outcall only. I did do 1 day per 6 weeks or so in a hotel seeing anything from 1 - 3 reliable incall clients. After about 12 months some weeks I could take the same cash wise as when I was incall.
Do bear in mind I've never been high volume, however there are times I'm turning bookings away, booked up for 3 or 4 days ahead, but I also demand a deposit from new clients which does put quite a few off.
Already being established probably helped, but as I say there are weeks when I'm doing as well as when I was incall except this time I don't have rent to pay or a second place to clean and maintain.
Opportunity to use a property for incall has arisen, however for discretion ad location reasons I can't see many clients there and I don't want to because I do just fine with outcalls. To the point where I fling on a hefty premium if someone wants put of hours or out of region travel.
Some say it's my rural location but quite a few clients are from areas, or travel to areas of plentiful access to other sex workers.
Whether any of this will work in London is another question, but I know that there it is possible to make a reasonable living on outcalls, and I have seen that anyone offering incalls will rarely get outcall bookings because the clients who contact them take incalls as first preference.