App development from my idea

I am looking for an experienced App developer (UK only please as you may be required to meet locally)

I would like an App developed that once finished can be EASILY edited by me through use of spreadsheets or an online back end (suggestions welcome)
I would need to be able to add for each client.. Text, input a date, a link to another website and be able to add an image.

The app is to be a "Whats On" guide.
Content would be uploaded by our staff but users of the App must be able to to search by proximity, date, and other various search criteria.

I would like to have the app available in 2 versions.. 1 Free which would include revenue earning adverts and a 2nd paid for version £1 max which would remove ads.

I would also like to include a daily push notification.