Changing to an electronic programmeable thermostat - a simple job?

I've recently moved house and the thermostat timer for the heating and hot water is a really old thing with a dial and some clips. Looking at I guess you can set it to be off between certain times ie when likely to be out at work, and then on between another time period when likely to be in. The only way to adjust the temperature is manually with the dial thats in the living room.

My old flat had an electronic timer, it used to be a set temperature between certain times ie 21 degrees between 5am and 9am, then it would drop down to 16 degrees between 9am to 4pm, it would then go up to 23 degrees from 4pm to 11pm before switching back down to 19 degrees between 11pm and 5am.

Is it possible to install one of these types of thermostat timers as a direct replacement? If so how easy a job would it be?

Thanks in advance for any thoughts