How long after my Tier 5 visa expires and I leave the UK should I wait before trying to reenter the country as a tourist

Hi there. I'm a US citizen and have been in the UK on a Tier 5 charity worker visa for nearly the past year. I'm planning to head to Europe at the end of July when my visa expires, but then I'd like to re-enter the UK several weeks later in mid-August as a tourist to participate in a retreat here. I would only stay for a week before leaving again to Europe, and I'd book my travel ahead of time so I could show evidence of planning to stay for just a week. Would the border agent admit me?

I'm also planning to return to the UK in mid-December, again as a tourist, for another retreat, and this time for 2-3 months. This second trip is more important to me than the first and I'm wondering whether trying to return in August, whether I'm admitted or not, would jeopardize my ability to return in December.

Any advice much appreciated! (and links to sources of any information cited also valued!)

There is no hard and fast rules about re-entry after an extended period on a work/study/volunteer visa. It is very much upto the Border Officer to determine the credibility and intent of returning individuals in the circumstances you have outlined.

As a rule of thumb if you are able to demonstrate your intention to leave the UK through pre booked airline tickets and onward accommodation then you are in a much stronger position. The one week return is likely to be ok as long as you are able to convince them you are not here to work or volunteer- have you paid to undertake the retreat?

The longer retreat I am seeing issues with a 2/3 month stay as it just does not seem credible that you would return again for a prolonged period so soon. Again are you paying to undertake the retreat?

The other issue is who are the retreats with? The same organisation or linked organisation as your Sponsorship? If yes - then that adds barriers as the thinking will tilt towards what are you doing while in the UK.