SQL Server 2012 :: Increment Date Based On Time Value Automatically

I have a client data which has the candidate id, a start date which will have only the date in varchar format and a time value associated to that date in varchar format in a seperate column.

To give a brief explanation about the data a candidate will come to study center at any time point in a day for example 10:00 AM on 20-10-2014. The start date will be 20-10-2014 and from 10:00 AM he will have test based on the time point. So if the time point is 2 HR, then at 12:00 PM he will have a test. If the time point is 8 HR, it will get added with 10:00 AM and based on this he will have the test at 06:00 PM. When the timepoint reaches 00:00 the start date needs to be the next date instead of 20-10-2014.

The start date needs to be appended with the time value such that when it crosses over the time 00:00, the start date needs to get increased by 1 ie the next day. I have added the start date to the time by using the code below

CAST(STARTDATE as datetime) + CAST(CAST(STUFF([TIME],3,0,':') as time(0)) as datetime) as [EXPECTEDDATETIME]

By this above code i have created the expected datetime however

I will not be able to hardcode the value due to dynamic data. I tried to apply >= and < to the time value something like

case when MyTime >= '00:00' and MyTime < '08:10' the Dateadd(day, 1, date)

This works perfect but my concern is that I cannot put the value 08:10 because it will not a constant value for all rows.

I have provided a screenshot of my data and a expected date column for reference.

Candidate StartDateStartTimeExpected DateTime Timepoint
1 20141020 1000 2014-10-20 10:00:00 0 HR
1 201410201200 2014-10-20 12:00:00 02 HR
1 201410201400 2014-10-20 14:00:00 04 HR
1 201410201800 2014-10-20 18:00:00 08 HR
1 201410200000 2014-10-21 00:00:00 12 HR
1 201410201200 2014-10-21 12:00:00 24 HR
2 20141020 1100 2014-10-20 11:00:00 0 HR

[Code] ....

I have also attached the data for reference.