The main aim of treatment is to keep your viral load low and eventually achieve viral suppression. The amount of adherence required to meet this point may vary slightly from person to person, it can also depend on the drugs that you are taking and other personal factors, such as if you have any other health conditions.
Clinicians generally use 95% adherence as the standard required for viral suppression. This means that your adherence should be close to perfect, but if you miss a dose once in a while it won't normally stop your HIV from being suppressed. If you keep forgetting your antiretroviral treatment, you need to speak to a healthcare worker about it. They'll be able to offer you some help.      

Taking breaks from your treatment is not recommended. Antiretroviral treatment is the only way to control HIV and keep your immune system healthy. It's important that people who stop taking antiretroviral treatment re-start again as soon as possible. If you have had a long break, you should see a healthcare worker before starting treatment again. They will want to check your overall health and may suggest that you take a different treatment this time.

Whether or not it matters if you take your antiretroviral treatment with food will depend on the specific drugs that you are taking. The main reason they give you advice around food is that it can change how your treatment is absorbed.

For example, taking efavirenz after a high-fat meal can mean that the amount of antiretroviral treatment absorbed by your body is far higher. This can make side effects worse and in worse cases lead to a level of the drug in your body that can be harmful. Other drugs require food in order to be fully absorbed, so make sure you understand and follow your healthcare worker's instructions.
If you are having problems following the advice about whether or not to take your antiretroviral treatment with food, let your healthcare worker know.