setting individual days on CH timer?

This has little do do with your gas boiler - just the timer programmer that turns it on and off.

Consider this approach - it's much easier and far less complicated.

Set the timer to be constantly on for both Heating and hot water.

Set the room thermostat to a setting you find comfortable and when you retire for the evening or leave to go to work turn the room thermostat down to a lower level - say 10 degrees C. When you return from work adjust the thermostat to your preferred temperature.

In my house there are two settings - 10 and 15. On a really cold night the radiators are lukewarm in the morning and the place soon warms up - there is always plenty of hot water.

Alternatively - we see on the TV the ability to adjust your Heating remotely using a smart-phone.

Alternatively you might consider something like this...
The Timeguard TRT036 7 Day Digital Heating Programmer is a two channel programmer dedicated to central heating and hot water, with automatic summer winter time changeover (which can be cancelled), 5 day plus 2 or 7 (individual) day programming, pumped or gravity fed system, holiday mode, boost function, advance to next program and permanent on/off over ride.

Good Luck...
January 2017