You can use the massive development chart to search on your developer - you will get times for a number of other films, including at least one Ilford film - Delta 100 Pro. That indicates 1 + 1 for 7 minutes at 20C.

You can then compare those times with the times that Ilford gives for Delta 100 in various developers, to determine which developer is closest to your developer. The Ilford chart indicates 7 minutes for Delta 100 Pro developed in stock ID11 at 20C - so I would use stock ID11 as the comparable.

The Ilford chart recommends 7.5 minutes for HP5+ developed in stock ID11 at 20C - so I would use that as my starting point for tests.

Here is the link to the Ilford chart: http://www.ilfordphoto.com/Webfiles/...1219521241.pdf

Warning: this is a rough and ready approach which is only really useful to find starting points.